thermal/of: Use generic thermal_zone_get_trip() function

thermal/of: Use generic thermal_zone_get_trip() function

The thermal framework gives the possibility to register the trip
points with the thermal zone. When that is done, no get_trip_* ops are
needed and they can be removed.

The thermal OF code uses the thermal_zone_device_register_with_trips()
function. It builds the trips array and pass it to the register
function. That means the get_trip_* ops are duplicated with what does
already the core code.

Remove them.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20221003092602.1323944-6-daniel.lezcano@linaro.org